The following abbreviations are herewith defined, at least some of which are referred to in the following description associated with the prior art and the present invention.    BRAS Broadband Remote Access Server    BTV Broadcast Television    CC Continuity Check    DA Destination Address    DHCP Dynamic Host Configuration Protocol    DSL Digital Subscriber Line    DSLAM Digital Subscriber Line Access Multiplexer    IEEE Institute of Electrical and Electronics Engineers    IP Internet Protocol    IPTV Internet Protocol Television    LAN Local Area Network    LB Loopback    LBR Loopback Reply    LT Line Termination (customer-side of a DSLAM)    NT Network Termination (network-side of a DSLAM)    MA Maintenance Association    MAC Media Access Control    MD Maintenance Domain    MEP Maintenance End Point    OAM Operation, Administration and Maintenance    OLT Optical Line Termination    ONT Optical Network Termination    PON Passive Optical Network    RGW Residential Gateway    TLV Type-Length-Value    TV Television
Referring to FIGS. 1-2 (PRIOR ART), there are two block diagrams of a traditional access network 100 with Ethernet-based DSL aggregation (e.g., see DSL Forum TR-101). The traditional access network 100 (e.g., IPTV network 100) includes a regional network 102 which is coupled to an edge router 104 (e.g., BRAS 104 with ports 105) which is coupled to one or more aggregation nodes 106 (with ports 106a and 106b). The aggregation node(s) 106 are connected by an Ethernet access network 108 to multiple access nodes 110 (e.g., DSLAMs 110 each of which include a NT card 113 which has NT exterior-facing ports 113a and NT interior-facing ports 113b and a LT card 115 which has LT interior-facing ports 115a and LT exterior facing ports 115b). The DSLAMs 110 are connected to multiple CPEs 112 (RGWs 112) which in turn are associated with multiple customers 114 where there is normally one customer 114 associated with one CPE 112. In one application, the BRAS 104 transmits BTV traffic 118 (multiple TV channels 118) at the Ethernet level (level 2) downstream via the aggregation node(s) 106, the Ethernet access network 108, the DSLAMs 110, and the CPEs 112 to the customers 114. The basic architecture and functionality of the traditional access network 100 is well known to those skilled in the art but for additional details about this type of architecture reference is made to DSL Forum TR-101 Ethernet-based DSL aggregation dated April 2006 (the contents of which are hereby incorporated by reference herein).
The traditional access network 100 typically implements a connectivity fault management scheme (EthCFM or EthOAM) that has been disclosed in the IEEE 802.1 ag/D8 standard entitled “Virtual Bridged Local Area Networks—Amendment 5: Connectivity Fault Management” Feb. 8, 2007 (the contents of which are incorporated by reference herein). The IEEE 802.1ag/D8 standard specifies protocols, procedures and managed objects that support connectivity fault management. These allow the discovery and verification of a path taken for frames addressed to and from specified network components like the BRAS 104 and the CPEs 112. As a result, connectivity faults can be detected and isolated to a specific component like one of the DSLAMs 110. Unfortunately, the traditional access network 100 when implementing this type of connectivity fault management scheme suffers from several problems:
1. The BRAS 104 periodically sends a multicast loopback (LB) message towards all of the CPEs 112 so as to discover the currently connected CPEs 112 and to obtain the MAC addresses of the currently connected CPEs 112. Upon receiving the LB message, the currently connected CPEs 112 respond by sending a unicast loopback response (LBR) message back towards the BRAS 104. The BRAS 104 receives many LBR messages from the currently connected CPEs 112. However, there is no current scheme that the BRAS 104 can use when analyzing the received LBR messages to verify the trustworthiness of the corresponding CPEs 112/customers 114.
2. The CPEs 112 often send CC messages towards the BRAS 104. Each CC message contains a MD/MA/MEP identification of the corresponding CPE 112. This MD/MA/MEP identification information is pre-configured at the BRAS 104. However, it is possible that a hacker can insert incorrect identifiers into CC messages which could disturb the OAM of the operator. For instance, the BRAS 104 could think a customer 114 (or business user 114) is still available because it receives messages from the MD/MA/MEP, while the customer 114 (or business user 114) might not be available and the messages are instead sent from a hacker.
Accordingly, there has been a need and still is a need for addressing these shortcomings and other shortcomings associated with the traditional access network 100 that implements the current connectivity fault management scheme. This need and other needs are satisfied by the present invention.